1. Field of the Invention
The field of art to which the claimed invention pertains is solid bed adsorptive separation. More specifically, the claimed invention relates to a process for the separation of isomers of nitrotoluene from a feed mixture comprising such isomers which process employs a solid adsorbent which selectively removes the selected isomers from the feed mixture.
2. Background Information
The nitrotoluenes are important starting materials for the manufacture of dyes and explosives. Ortho-nitrotoluene, in particular, is used in the synthesis of dyes such as New Magenta. Para-nitrotoluene is used for the synthesis of Turquoise Blue.
The conventional method of separating isometric mononitrotoluenes involves complex distillation followed by crystallization procedures that are tedious and expensive to conduct.
It is known from U.S. Pat. No. 4,270,013 to Priegnitz et al. that ortho-nitrotoluene may be separated from other nitrotoluene isomers by using a type X zeolite containing at exchangeable cationic sites one cation selected from a group that includes potassium and barium. The specific desorbent materials disclosed by this reference are toluene and 1-hexanol.
I have discovered a method of employing zeolites for the separation of nitrotoluene isomers, particularly the ortho from a mixture of the isomers, which uses a specific desorbent material uniquely suitable for that separation.